Light barrier for fungal toxins – Researchers at the Max Rubner-Institut inhibit the production of toxins

Researchers at the Max Rubner-Institut have developed a process that may not completely kill the moulds, but effectively inhibits their growth: certain wavelengths of visible light disrupt the rhythm of life of many forms of mildew so successfully that they stop producing fungal toxins and in the best-case scenario, stop growing altogether.

Ochratoxins are the toxins of a large group of mildews, which also includes various Penicillium and Aspergillus species. Like most living organisms these moulds have a biological clock that regulates growth and metabolism. At the beginning of the project, Prof. Rolf Geisen, a researcher at the Max Rubner-Institut, suspected that “if we can manage to change the rhythm of this clock, then we can stop the production of toxins.”

Blue light with a wavelength of 450 nanometres has proven to be a particularly effective inhibitor. “We don’t use harmful UV radiation. The blue light is sufficient to destroy 80 per cent of the mould spores,” says Dr. Markus Schmidt-Heydt, a researcher in Prof. Geisen’s team. On the other hand, researchers have also discovered that yellow and green light promotes the growth of the moulds. Moulds are therefore certainly not ‘blind’. They have light receptors for different wavelengths. Unfortunately, however, the varieties of mould have different levels of sensitivity. Typical cereal moulds like the Fusaria react differently to being illuminated, producing higher levels of light protection pigments like carotin, for instance.

This discovery is being intensively tested for its practical application in the context of the EU project “Novel strategies for worldwide reduction of mycotoxins in foods and feed chain” (MycoRed). If the illumination strategy meets its promise in the practical testing stage then this would be a huge step forward in the battle against the spoilage of food in Germany and throughout the world.